Many years ago a friend of mine was working on a mocked up ATM type system that ran over a serial line. This included some self-tests to make sure that the line was up and running okay.

When writing the self-test code he kept hitting this problem where the working test line was being diagnosed as failing. Spent most of a day going over the assembler code in question. We got to the stage where we were questioning the serial driver hardware in the machines and were looking around for spares.

Very late that day we finally thought to check that the test lead was actually working... You should have heard the howls when we realised we'd wasted most of a day on some dodgy wiring.

I still look back at that and wonder at our complete inability to accept that a few hundred bytes of obvious code was working properly. We knew that it must be a bug :-)

It proved a salutary lesson for me. Always try and disable your assumptions when debugging and look at what is actually happening.

In reply to Re: Suspending Disbelief While Debugging by adrianh
in thread Suspending Disbelief While Debugging by dws

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.